Debian LinuxOperating system · Debian
CVE-2013-4559
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedlighttpd before 1.4.33 does not check the return value of the (1) setuid, (2) setgid, or (3) setgroups functions, which might cause lighttpd to run as root if it is restarted and allows remote attackers to gain privileges, as demonstrated by multiple calls to the clone function that cause setuid to fail when the user process limit is reached.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencelighttpd before 1.4.33 fails to check return values from setuid(), setgid(), and setgroups() calls used for privilege dropping. When these functions fail (e.g., due to process/thread limits), lighttpd continues running as root instead of properly handling the error, allowing privilege escalation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Debian LinuxOperating system
= 6.0= 7.0= 8.0< 1.4.33= 12.2= 12.3= 13.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:H/Au:N/C:C/I:C/A:C
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify lighttpd versionRun 'lighttpd -v' or 'lighttpd -version' to get the installed version numberAffected if Version is below 1.4.33 (e.g., 1.4.32, 1.4.31, etc.)
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Check lighttpd configuration for privilege droppingExamine the configuration file (commonly /etc/lighttpd/lighttpd.conf) for 'server.username' and 'server.groupname' directives, or 'var.basedir' settings that reference user/group configurationAffected if Configuration includes user/group settings that trigger setuid/setgid calls (e.g., server.username = "www-data" or server.groupname = "www-data")
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Verify if lighttpd runs as root initiallyCheck the process startup method (init script, systemd unit, or command line) to determine if lighttpd is started as root before dropping privilegesAffected if Lighttpd is started as root and configured to drop privileges to a non-root user (the vulnerability only triggers when running as root and attempting to drop privileges)
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Check system resource limitsReview system limits for max processes/threads (ulimit -u) and compare against current usage; also check /etc/security/limits.conf for any restrictionsAffected if System has low process/thread limits that could cause setuid/setgid/setgroups to fail, combined with lighttpd running as root and attempting privilege dropping
You are affected if lighttpd version is below 1.4.33, the server is started as root with user/group privilege dropping configured, and the vulnerable code path executes.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data1.4.33
Upgrade to lighttpd 1.4.33 or later which includes proper return value checking for privilege-dropping system calls.
Fix this in Debian Linux
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,144.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-4559 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2013-4559 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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